A Fulfilment of the Sunday precept is described most succinctly in Canon 1247: “On Sundays and other holy days of obligation, the faithful are obliged to participate in the Mass.” Canon 1248 §1 goes on to explain what this means: “A person who assists at a Mass celebrated anywhere in a Catholic rite either on the feast day itself or in the evening of the preceding day satisfies the obligation of participating in the Mass.” For example, a Catholic can attend a Roman Rite Mass for the given Sunday; a Ritual Mass permitted by the calendar, such as a Confirmation, a wedding, or the dedication of a church (that’s right: the Mass need not use the readings or prayers for the particular Sunday—a common misconception); or a divine liturgy according to an eastern Catholic Church, such as the Maronite or Greek Catholic.
But if such attendance in person is not possible, the Code suggests other ways to mark the Lord’s Day—even though these do not fulfil the obligation: “If participation in the eucharistic celebration becomes impossible because of the absence of a sacred minister or for another grave cause, it is strongly recommended that the faithful take part in a liturgy of the word if such a liturgy is celebrated in a parish church or other sacred place according to the prescripts of the diocesan bishop or that they devote themselves to prayer for a suitable time alone, as a family, or, as the occasion permits, in groups of families” (Canon 1248 §2; emphasis added). In other words, the Televised Mass can never fulfil one’s Sunday obligation to attend Mass, whether one is able to attend Mass in a church or not. But where it is impossible to attend Mass in person, the Televised Mass may be a laudable, although unnecessary, means to pray on the Lord’s Day.
One further thing to note is that the Sunday precept is not entirely fulfilled by attending Mass. As Canon 1247 goes on to say, in addition to Mass, the faithful are also “to abstain from those works and affairs which hinder the worship to be rendered to God, the joy proper to the Lord’s day, or the suitable relaxation of mind and body.” Attending Mass and refraining from unnecessary work are the Sunday essentials.